In a computer device, an LSI is Packaged and is implemented (or mounted) on a circuit board. The LSIs have been mounted on wiring board while they are housed in a package. The structure of such a package is generally known from Japanese Patent Kokai Publication JP 11-17058A. The known package structures are provided in the form of BGA package in which the LSIs are sealed in a mould resin so that they will not be exposed. The BGA Package is bonded on a wiring board. The BGA board has a surface area which is smaller than that of the wiring board. The BGA board to be connected in a face-up manner will be connected to the wiring board by a wire bonding technique. In such a package structure, signals are fed out from the BGA board via solder balls provided on a reverse side of the BGA board.